Embodiments of the invention described herein relate to a method and device for producing electricity by conversion of the mechanical energy of waves such as ocean waves in a water body.
Identification of new non-fossil fuel based energy sources that are both commercially viable and environmentally benign has become a vital technological need for the next century. Such technology will not only fuel economic growth and contribute to global environmental sustainability, but also reduce a nation's energy dependence on foreign oil in coming decades.
The world's oceans have long been thought of as sources of tremendous energy, with the global capacity estimated to be around 2 terra-Watts. Successful harvesting of energy from the ocean can help to relive the load at the point of demand on some of the most heavily populated regions of the United States. A survey conducted by the National Oceanic and Atmospheric Administration (NOAA) found that approximately 153 million people (53 percent of the nation's population) lived in the 673 U.S. coastal counties. Many nations around the world including the United Kingdom, Australia, China and India have densely populated coast-lines that can benefit substantially by harvesting power from ocean waves.
There are several methodologies of tapping energy from the oceans, and these methods can be broadly divided into thermal, tidal, and wave techniques. Of these various methods, the harvesting of wave energy is of particular importance. Within the area of wave energy harvesting, devices can again be sub-divided into on-shore and off-shore devices. Off-shore power devices tap the energy available from ocean waves using an oscillating water column type device. Efforts to tap the seemingly unlimited energy available through harvesting of ocean waves have proven to be difficult.
Large scale efforts to tap energy from the ocean continue to be hampered by high energy costs and low energy densities. It is estimated that the energy cost per kW from ocean energy with conventional technologies is around 20 cents/kWh, a level at which some form of subsidies are required for the technology to be widely adopted. In addition, hidden costs include the possibility of high replacement costs in the event of catastrophic failure or damage during major storms.